1. Field of the Invention
The invention relates to a mechanism for adjusting the stitch density of circular knitting machines of the type having a stationary external portion with a programmable controller and a rotating portion whereon there is mounted a plurality of cam supports, each having a front surface, facing a stationary needle bed and provided with a cam set including a stitch cam, and a rear surface from which there extends a base portion towards said stationary external portion.
2. Description of the Prior Art
With regard to stitch density, knitting machines may generally be subdivided into two major groups, i.e.
those in which it is not possible to vary the density of the stitches knitted by the knitting sets simultaneously with the knitting process and which, therefore may only knit continuous pieces; and
those in which it is possible and which, therefore, are adapted to knit garment lengths.
Within the latter group, there are several embodiments of the known art for adjusting the knitted stitch density simultaneously with the knitting process.
In one embodiment, each stitch cam has associated therewith a stepping motor which moves the cam through a mechanical link. There are two drawbacks to this solution: first, the high cost, particularly onerous in the case of machines having many sets and, second, a wide transition zone of stitch density corresponding to the time/space required by the stepping motor to move the cam is created in the fabric.
A further conventional mechanical solution consists of centralizing a change control on the stationary portion of the machine and associating a mechanical control having 6 or 8 preprogrammed positions with the stitch cam of each section.
The control associated with each stitch cam is provided with a star wheel which on engaging a lever of the fixed control causes it to rotate 1/6 or 1/8 turn, which involves the change of position of the stitch cam. Although this solution is cheaper, it is limited in that it is not possible to program more than a limited number of stitch densities and, furthermore, these must be repeated throughout the garment.